Objective      To determine the effect of transfection of ultrasonic microbubble with herpes simplex virus thymidine kinase (HSV

1

-TK) gene on prostate cancer cell line PC-3 combined with ganciclovir (GCV).       Methods      MTT assay was used to test the optimal irradiation time of PC-3 cells by ultrasonic irradiation. Ultrasound microbubble surface was adsorbed with HSV

1

-TK gene

and then tran

sfected into PC-3 cells under optimal ultrasound irradiation. Fluorescence microscopy and Western blot analysis were used to detect the transfection and expression of TK. The cell proliferation was measured by MTT assay after the treatment of different concentrations of GCV. Flow cytometry (FCM) was used to measure the cell cycle of the transfected PC-3 cells after the treatment of the optimal concentration of GCV. The killing effect of HSV

1

-TK/GCV suicide gene system on prostate cancer cell PC-3 was observed by MTT assay.        Results      MTT assay showed that ultrasonic radiation had no significant inhibition on cell viability under the conditions of the magnitude of 1.0 W/cm

2

frequency of 1 MHz

and every 30 s ultrasound exposure time. HSV

1

-TK was transfected into PC-3 cells by ultrasound wave irradiation and expressed stably. Compared with the control

the killing activity of ultrasound radiation+ microbubble + TK treatment with the GCV concentration of 100 μg/ml was obviously higher

with cell survival rate of about 32%

significantly lower than the other group (P0.05). FCM showed that most cells were blocked in S phase

and cell growth was obviously inhibited.       Conclusion      Transfection of suicide gene by ultrasound microbubble and the application of GCV has an obvious effect on the apoptosis of human prostate cancer cells.